Conventionally, there are devices described in Patent Literature 1 and Patent Literature 2 as a power source outlet device having a function of detecting occurrence of tracking. Patent Literature 1 discloses a technique where two tracking detecting electrodes are disposed between plug insertion holes, an exciting coil of a release relay is connected between the tracking detecting electrodes, and the exciting coil is excited by a tracking current generated between the plug insertion holes so that the release relay behaves to break a cable run.
Patent Literature 2 discloses a technique where a current detecting section, a filter circuit, an A/D converting circuit, a processor, and the like are provided, and determination about occurrence of tracking is made based upon a detected cable run current.
[Patent Literature] JP-A-09-180805
[Patent Literature] JP-A-2001-324533